Lack of vitamin D may cause MS, study finds

[MSUK]

A lack of vitamin D may be a direct cause of multiple sclerosis (MS), a study has found. Researchers say the discovery may have important public health implications since so many people have insufficient levels of the essential vitamin... Read More - http://www.ms-uk.org/vitaminD

[NHE]

Vitamin D and Risk of Multiple Sclerosis: A Mendelian Randomization Study.
PLoS Med. 2015 Aug 25;12(8):e1001866.

• BACKGROUND: Observational studies have demonstrated an association between decreased vitamin D level and risk of multiple sclerosis (MS); however, it remains unclear whether this relationship is causal. We undertook a Mendelian randomization (MR) study to evaluate whether genetically lowered vitamin D level influences the risk of MS.
  
  METHODS AND FINDINGS: We identified single nucleotide polymorphisms (SNPs) associated with 25-hydroxyvitamin D (25OHD) level from SUNLIGHT, the largest (n = 33,996) genome-wide association study to date for vitamin D. Four SNPs were genome-wide significant for 25OHD level (p-values ranging from 6 × 10-10 to 2 × 10-109), and all four SNPs lay in, or near, genes strongly implicated in separate mechanisms influencing 25OHD. We then ascertained their effect on 25OHD level in 2,347 participants from a population-based cohort, the Canadian Multicentre Osteoporosis Study, and tested the extent to which the 25OHD-decreasing alleles explained variation in 25OHD level. We found that the count of 25OHD-decreasing alleles across these four SNPs was strongly associated with lower 25OHD level (n = 2,347, F-test statistic = 49.7, p = 2.4 × 10-12). Next, we conducted an MR study to describe the effect of genetically lowered 25OHD on the odds of MS in the International Multiple Sclerosis Genetics Consortium study, the largest genetic association study to date for MS (including up to 14,498 cases and 24,091 healthy controls). Alleles were weighted by their relative effect on 25OHD level, and sensitivity analyses were performed to test MR assumptions. MR analyses found that each genetically determined one-standard-deviation decrease in log-transformed 25OHD level conferred a 2.0-fold increase in the odds of MS (95% CI: 1.7-2.5; p = 7.7 × 10-12; I2 = 63%, 95% CI: 0%-88%). This result persisted in sensitivity analyses excluding SNPs possibly influenced by population stratification or pleiotropy (odds ratio [OR] = 1.7, 95% CI: 1.3-2.2; p = 2.3 × 10-5; I2 = 47%, 95% CI: 0%-85%) and including only SNPs involved in 25OHD synthesis or metabolism (ORsynthesis = 2.1, 95% CI: 1.6-2.6, p = 1 × 10-9; ORmetabolism = 1.9, 95% CI: 1.3-2.7, p = 0.002). While these sensitivity analyses decreased the possibility that pleiotropy may have biased the results, residual pleiotropy is difficult to exclude entirely.
  
  CONCLUSIONS: A genetically lowered 25OHD level is strongly associated with increased susceptibility to MS. Whether vitamin D sufficiency can delay, or prevent, MS onset merits further investigation in long-term randomized controlled trials.

[Scott1]

Hi,

If they draw that conclusion then they should look at the precursors of Vitamin D, how they are converted into Vitamin D and what is required for that to happen. Just measuring Vitamin D won't tell you much except the levels in the cohort. Sunlight has an influence so that has to be allowed for, other health problems can influence results.
Pleiotropy is acknowledged but not investigated. I think this is like so many other circular arguments.
As discussed here - http://ndt.oxfordjournals.org/content/17/11/1867.full "it has been demonstrated that the megalin cubilin-mediated reabsorption of vitamin D binding protein is responsible for the renal conversion of 25(OH)D3 to 1,25(OH)2 D3 in the proximal tubule". That was written in 2002. It's a pity they don't read their peers articles instaed of repeating themselves.

Regards

[Leonard]

The matter is complicated; not a straight-forward causal relationship.

Vitamin D blocks the EBNA receptor which impedes EBV; interferon is anti-viral.

But they also influence each other!

In some cases (e.g. own case) vitamin D was regulated down by the body. A protective reaction?

Following Scott last comment, in Dutch we have a saying that says: "Waar iedereen hetzelfde denkt, denkt niemand veel" which translates into something like "Where everybody thinks the same, no one thinks a lot".

[1eye]

Scott, Leonard...

How many years have I been hearing this? Neurologist Dr. OConnor wrote in his book "MS The Facts You Need" that you need 4000 IU of D per day. It is a fairly old book.

I guess someday, like evolution, it will graduate from a theory to a fact.

Like everything else: more research is needed.

http://www.thestar.com/news/gta/2015/06 ... again.html